In CAPD, a catheter made of silicone rubber having a diameter of 4 to 6 mm is implanted in an abdominal cavity of a renal insufficiency patient. A dialysate is injected into the abdominal cavity through this catheter, and dialysate that has stayed in the abdominal cavity is drained through the catheter after a few hours. In this way, a dialysis therapy is carried out.
A plurality of side holes, which are through-holes for draining, are formed at a tip end portion of the catheter. The catheter is implanted such that the tip end portion is positioned at a Douglas' pouch of the abdominal cavity. As the catheter is in an implanted state in the abdominal cavity for a long period of time, a membranous greater omentum that is within the abdominal cavity tangles with the tip end portion of the catheter to close side holes. Thus, there are problems in that draining from the abdominal cavity to outside becomes difficult, and consequently pain or discomfort occurs.
Japanese Patent Application Laid-Open (JP-A) No. 9-10315 discloses a catheter in which a tip end portion of an inner tube, at which tip end portion a plurality of side holes are formed, is covered with an outer tube and a bypass path is formed by a groove formed at an outer surface of the inner tube or at an inner surface of the outer tube, and thus even if side holes are closed, a cerebrospinal fluid can be evacuated via the bypass path.
However, there has been a problem in that it is difficult to manufacture a conventional catheter because the tip end portion at the catheter is formed by a double tube. Further, there is a problem that, because there is a double tube, if an outer diameter of a catheter is made small in order to reduce volume and obtain excellent implantation in an abdominal cavity, an inner diameter is reduced and draining cannot be performed well. Moreover, there could also be a problem that total draining may become impossible if the tip end portion alone is closed.
Further, JP-A No. 8-206219 describes a medical drain tube in which a plurality of grooves are formed at an outer surface of the tube in a length direction thereof, and a plurality of side holes are formed at a bottom surface of each groove.
In JP-A No. 8-206219, as the side holes are formed at the bottom surfaces of the grooves, a width of the grooves is larger than the side holes. At a time of draining-out, body tissues in vicinities of the grooves enter a little into portions of the grooves. In the state in which the body tissues have entered a little into the portions of the grooves, the side holes are not closed, and a discharge fluid flows through the grooves from the side holes into a lumen. At this time, since the tissues enter the grooves and abut corner portions of the tube that form the grooves, pain is caused to a patient. Accordingly, lightening of discomfort such as pain at the time of draining cannot be expected.
Also, the side holes are formed at the bottom surfaces of the grooves and do not communicate with each other. Thus, if draining is performed by suction by air, the side holes are closed by body tissues, draining cannot be performed through the closed side holes and as the suction proceeds, the body tissues enter into the side holes, which causes pain to the patient.
The present invention was developed in order to solve the above-described problems, and an object of the present invention is to provide a catheter of which manufacturing is easy and in which, even if volume is made small, inner diameter does not become small and draining can be performed well.